Ethernet can operate in two basic modes: 1) Carrier Sense Multiple Access with Collision Detection (CSMA/CD), known as Half Duplex or Shared Ethernet, and 2) Point-to-Point, known as Full Duplex or Switched Ethernet. As the data rates increase, either the network diameter decreases or the slot time must increase because of the round-trip delay constraint imposed by CSMA/CD. The round-trip delay constraint for collision detection provides that the time to transmit a packet must be greater than the round trip time for a signal to travel between the two farthest stations; i.e., it must send at least twice the total cable length in bits for any transmission.
For currently implemented 1-Gigabit Ethernet (GbE), the slot time had to be increased to 512 bit times to give a reasonable network diameter of 300 meters. This large slot time leads to high overhead for small packets, so the throughput decreased. Packet bursting was used to improve this throughput.
For 10 GbE and higher these trade-offs between slot time and network diameter become more unpalatable, so shared (half duplex) Ethernet is not an extremely attractive option. Full duplex Ethernet does not suffer from this restriction in round-trip delay time. Current networks have been converting to switched (full duplex) Ethernet as switching technologies have become more cost effective to provide higher performance. Thus, the need for half duplex operation is becoming a smaller factor. For the higher speed Ethernets, such as 10 GbE and beyond, half duplex operation is non-existent.
There is a desire to use Ethernet technology to displace ATM, Frame Relay, and SONET in the core network, providing end-to-end Ethernet connectivity. The advantages of end-to-end Ethernet connectivity include (i) fewer technologies to support; (ii) simpler, cheaper technology due to eliminating the complex, expensive SONET connections; (iii) elimination of expensive protocol conversions that get more difficult as the data rates increase; (iv) improved support for Quality of Service (QoS) because protocol conversions can lead to a loss of the priority fields; and (v) improved security because security features may not be retained through the protocol conversions.
Newer applications are driving the data rates of the core network, as well as the local networks, continually higher. Currently, 1 GbE is readily available and 10 GbE is becoming more common. The Galaxy-V6 system provides 1 GbE network interfaces and uses 10 GbE HiGig inter-connections between the routing nodes and the switch modules. Still, the demand for even higher data rates has continued. Applications driving these increased data rates include (i) grid computing; (ii) large server systems; (iii) high performance building backbones; and (iv) high capacity, long lines. However, current switching systems have been unable to provide switching of frames at data rates much higher than 10 Gigabits/second.
Therefore, there is a need in the art for an improved switching system that is capable of switching frames at data rates higher than 10 Gigabits/second. In particular, there is a need for a switching system that is able to switch Ethernet frames at data rates of up to 100 Gigabits/second and higher.